1. Field of the Invention
The present invention relates to a method for laying a rehabilitating pipe wherein a rehabilitating pipe is laid inside an existing pipe such as a sewer pipe to rehabilitate the existing pipe.
2. Description of the Prior Art
A method of rehabilitating an existing pipe is known, for example, from Japanese Patent Laid Open Publication No. 2003-286742 in which an existing pipe such as a sewer pipe is rehabilitated using a rehabilitating pipe whose outer diameter is slightly less than the inner diameter of the existing pipe. A filler is filled and hardened in a gap between the outer periphery of the rehabilitating pipe and the inner wall surface of the existing pipe to construct a compound pipe comprising the rehabilitating pipe, the filler, and the existing pipe. The rehabilitating pipe is assembled by coupling segments in the circumferential direction and the longitudinal direction of the pipe. One segment corresponds to a block shaped member obtained by segmenting the rehabilitating pipe in its circumferential and longitudinal directions of the pipe.
Due to its own weight and the weight of the filler filled after assembly, the assembled rehabilitating pipe unfortunately deforms into a distorted shape so that it breaks in the downward direction if left as is. Conventionally, various methods have been employed as countermeasures, such as to increase the thickness and strength of the segments; to accessorily provide steel reinforcing rods in a ring shape around the outer periphery of the rehabilitating pipe; and, before filling with the filler, to install inside the rehabilitating pipe supports, such as struts, at intervals of several meters in the longitudinal direction.
In addition, at a position where the outer periphery of the lower end of the rehabilitating pipe contacts the bottom of the existing pipe, it is necessary to position the center of the rehabilitating pipe so that it is directly below the center of the existing pipe; however, because the specific gravity of the rehabilitating pipe is less than that of the filler, the rehabilitating pipe unfortunately floats above the aforementioned position if left as is. To avoid this, spacers are conventionally inserted from the left and right of the rehabilitating pipe between the outer periphery of the upper side of the rehabilitating pipe and the inner wall surface of the existing pipe, and pressed so that the rehabilitating pipe does not float upwards, thus positioning the rehabilitating pipe at the aforementioned position.
If the segments are made thicker, then there is a problem in that the weight of the segments increase, thus increasing the burden on the workers performing the assembly of the rehabilitating pipe; in addition, the amount of resin filled in the segments also increases, thus unfortunately leading to a cost increase. In addition, there is a problem in that the work involved in the method of accessorily providing steel reinforcing rods in a ring shape is extremely troublesome and time consuming. In addition, there is also a problem in that, in the method of installing the supports, the supports hinder the workers who move inside the narrow rehabilitating pipe when performing the work of filling with the filler, thus degrading working efficiency; in addition, it is necessary to perform the work of removing the supports after hardening of the filler. In addition, the deformation of the rehabilitating pipe cannot be prevented just with the method that presses down on the upward rise of the rehabilitating pipe with spacers, and it is consequently unfortunately necessary to also use, in parallel, one of the aforementioned methods of preventing deformation.
It is therefore an object of the present invention to provide a method for laying a rehabilitating pipe wherein the deformation and upward rising of the rehabilitating pipe can be prevented, and wherein the work of laying the rehabilitating pipe can be performed more simply and in a shorter period of time with the weight and cost of the segments reduced.